As a method for manufacturing a ceramic substrate having via holes, co-firing method (simultaneous firing method) and post-firing method (sequential firing method) are known. The method for manufacturing a substrate with via holes by co-firing method is a method including the steps of: forming a through hole in the pre-firing ceramic substrate precursor, i.e. the so-called “green sheet”; filling a metal paste into the through hole to produce a ceramic substrate precursor; thereafter, firing the obtained ceramic substrate precursor. By the method, firing of the green sheet and the conductive paste in the via hole is carried out simultaneously.
Meanwhile, post-firing method means a method including the steps of: applying a metal paste and a ceramic paste over a fired ceramic substrate; and then, firing the paste together with the sintered substrate. The method for manufacturing a substrate with via holes by post-firing method is a method including the steps of: piercing a sintered ceramic substrate obtained by firing a green sheet by laser method, machining, and the like to form through holes; filling a conductive paste in the through hole to form a ceramic substrate precursor; and firing the ceramic substrate precursor. By the method, firing of the green sheet and the conductive paste in the via holes is carried out sequentially.
For example, Patent document 1 discloses a method for manufacturing an aluminum nitride substrate by co-firing method. Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 11-135906